Outline of Alternative Pathways

Alternative Pathways

1. Why alternative pathways are needed

• environmental restrictions
  • light restrictions
  • water availability

• real world examples= desert, salt marsh, tropical

• Where the adaptions in photosynthesis occur
  • alternative pathways precede calvin cycle

2. C4 Plants

• severe heat conditions
  • keep stomata closed
  • 4 carbon storage/uptake balance

• real world examples= Corn, Sugarcane

• where process occurs
  • mesophyll cells (unlike C3 plants)

3. CAM Plants

• Day Cycle
  • stomata closed
  • calvin cycle only

• Night Cycle
  • stomata open
  • sugar production stages of photosynthesis
  • highest productivity

• where process occurs
  • bundle sheath cells (just at a different time of day than C3)

• physical attributes
  • thicker waxy cuticle
  • sunken stomata
  • tough fibrous structure

• real world examples= cacti, pineapple

Students Should Be Able To : By
- compare and contrast normal vs. alternative photosynthesis pathways : using a graphic organizer
- explain the Calvin Cycle : diagram the movement of carbon atoms (6)
- visualize and understand the purpose of the organelles in photosynthesis : draw and label structures and their role(s)
- Write an argument/defense of why or why not we need plants.